In the prior art, when frequency synthesizers and the like are constructed it is common to use separate RF and digital modules to get proper RF isolation. This adds substantial weight, apparatus and cost to the structure.
A typical shielded RF circuit is disclosed in U.S. Pat. No. 3,816,911 entitled "Shielding Techniques For RF Circuitry", issued June 18, 1974 and assigned to the same assignee. In the above described patent thin metal strips are formed by chemical etching, which strips include bend or fold grooves similarly etched. The strips are then bent into the desired configuration at the time of assembly. The chemical etched strips are formed into side walls, bottom walls and top walls with tabs provided between the edges of the strips holding the boards and the various strips in place. Substantial assembly time is required for the apparatus and separate printed circuit boards are used for each circuit within each separate compartment.